Wheel for forming package components and housing components

Abstract

[Solution] A foil for forming a package or housing, comprising: a bonding layer configured to be bonded to a metal foil; a core layer having a thickness at least half the thickness of the foil; and a sealing layer configured to be in permanent contact with an electrolyte.

Description

Technical Field

[0001] The present invention relates to a foil for forming a package member and a housing member. The present invention particularly relates to a foil for forming a reliably sealable package member or housing member for an electrolyte-containing substance or an electrolyte-containing structure in combination with a diffusion barrier. Background Art

[0002] Electrolyte-containing substances and electrolyte-containing structures are used in a wide range of applications in the electrical, automotive and chemical industries. Electrolyte-containing substances are either packaged for further processing or form corresponding structures in the form of electronic components such as batteries. The latter, in particular batteries, are the subject of intensive further development in the fields of consumer electronics, electric vehicles, and stationary storage devices for electrical energy.

[0003] Packaging and housing for such electrolyte-containing substances or electrolyte-containing structures must have certain properties that guarantee safe encapsulation of the substances and structures. In particular, the function of a diffusion barrier that effectively prevents leakage and loss of electrolyte components plays an important role herein. For such purposes, metal foils are conventionally used and generally provide sufficient diffusion barrier properties. Metal foils can be easily formed into package members or housing members because they favorably maintain the shape obtained by compression molding, or in any case maintain flexibility and malleability. Packaging containers such as bottles and pouches, as well as housings for permanent encapsulation, can also be reliably provided by this method.

[0004] While metal foils generally possess excellent diffusion barrier properties and are easy to process, they have certain drawbacks in terms of sealing. Clearly, it is necessary to securely encapsulate a substance or component in both packaging and housing. Therefore, it is often required to securely join and seal metal surfaces at seams to ensure the encapsulation of electrolytes. Although metals are generally easy to weld or solder, this involves significant heat input and energy consumption. [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, in the manufacture of package members or housing members that reliably enclose electrolytes, electrolyte-containing substances, or corresponding components, it is required to reliably bond the diffusion barrier.

[0006] Therefore, the present invention aims to provide a foil for forming a package or housing that reliably encapsulates an electrolyte while balancing overall advantages in terms of processability, weight, and energy consumption. [Means for solving the problem]

[0007] The aforementioned advantages and further advantages are provided by the foil described in claim 1. Further advantageous aspects of the present invention are defined in the dependent claims.

[0008] According to one aspect of the present invention, a foil for forming a package or housing is provided, comprising: a bonding layer configured to be bonded to a metal foil; a core layer having a thickness at least half the thickness of the foil; and a sealing layer configured to be in permanent contact with an electrolyte. [Brief explanation of the drawing]

[0009] Several embodiments of the present invention will be described in more detail with reference to the following drawings. This corresponding description is intended to better understand the teachings and associated advantages of the present invention and should not be interpreted as limiting in any way. The drawings show the following: [Figure 1] Figure 1 is a schematic diagram showing the basic structure of a foil according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the basic structure of a package intermediate product or housing intermediate product using foil according to one embodiment of the present invention. [Figure 3] Figures 3A to 3E schematically show the possible shapes of a package member or housing member made of foil according to one embodiment of the present invention. [Figure 4] Figures 4A and 4B schematically illustrate possible applications of the foil according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] Figure 1 schematically shows the basic structure of a foil according to one embodiment of the present invention. The foil 10 is used for packaging or housing, and in particular for containing electrolytes, electrolyte-containing substances, or electrolyte-containing structures. The uses and shapes of the corresponding packaging and housings will be described in more detail in relation to further embodiments. The foil 10 is preferably a product of co-extrusion molding. In co-extrusion molding, the materials of individual layers are combined in a molten state and extruded from an extrusion die or extrusion port to solidify as foil 10. In this way, the characteristics and strength (thickness) of each layer are determined by the corresponding number of intermediate products and their proportions. The foil 10 can be provided as a whole as a cast foil, and in particular as a cast polypropylene (CPP) foil, as long as polypropylene or other polyolefin plastics are used.

[0011] The foil 10 comprises a bonding layer 101 configured to be bonded to a metal foil. For bonding the bonding layer 101, an adhesion promoter may be used as needed, so that the properties of the bonding layer 101 are suitable for either direct bonding to the metal foil or bonding to the metal foil via an adhesion promoter. Such an adhesion promoter can be imparted, for example, by adding an adhesion-promoting additive to the bonding layer during extrusion molding. Furthermore, the adhesion promoter can also be imparted via a (separate) bonding system or adhesive (glue). In the latter case, for example, an adhesion promoter in the form of a bonding system can influence the properties of the bonding layer at least indirectly via the metal foil. The bonding layer 101 may consist solely of, or at least contain, a polyolefin plastic such as polypropylene. The bonding layer 101 may be corona pretreated, for example, with an adhesion promoter (e.g., an aluminum bonding system), to ensure good bonding to the metal foil or metal layer in subsequent manufacturing processes. (e.g., using a).

[0012] The bonding layer 101 is preferably subjected to corona pretreatment. By performing such corona pretreatment, the surface tension of the bonding layer can be increased compared to an untreated layer. For example, the surface tension can be increased to more than 30 mN / m (dyne), preferably more than 38 mN / m (dyne). The surface tension can be measured by a dyne test ink pen or contact angle measurement, and is therefore a characteristic of the corresponding embodiment. Corona pretreatment can advantageously improve the bonding of the bonding layer to the metal foil, especially when using a selective adhesion promoter or adhesive. The bonding layer 101 can also be directly bonded to the metal foil by thermal lamination. The bonding layer 101 may have a layer thickness in the range of 4 μm to 20 μm, or preferably in the range of 5% to 20% of the thickness of the foil 10.

[0013] The foil 10 further comprises a core layer 102, which particularly contributes to achieving the desired elasticity, toughness, and / or performance strength of the overall structure of the foil 10 and / or the package member or housing member. Therefore, the layer thickness dKE of the core layer 102 is at least greater than half of the foil thickness d, and preferably substantially equal to or greater than 70% of the foil thickness d. The core layer 102 may have a layer thickness in the range of 20 μm to 200 μm.

[0014] The foil 10 further comprises a sealing layer 103 configured to permanently contact the electrolyte. This sealing layer can also seal well with other sealing layers, for example, with other areas of the same sealing layer on the same foil, providing a reliable seal. The sealing can be performed by thermal induction welding or ultrasonic welding. The sealing layer is characterized by forming a high-strength sealing seam. The sealing layer is further characterized in having a low sealing point, i.e., sealing at relatively low temperatures, preferably from 100°C. For this purpose, special PP polymer types modified during manufacturing can be used so as to achieve a lower sealing point than ordinary unmodified PP and provide a very durable sealing seam. The sealing layer can be further characterized in that the sealing function does not change significantly even when the sealing surface is wet with the electrolyte.

[0015] Examples of such electrolytes include lithium phosphate, such as lithium hexafluoride phosphate dissolved in ethylene carbonate, dimethyl carbonate, and / or diethyl carbonate. Advantageous properties for resistance to permanent contact with the electrolyte may be chemical resistance and the migration behavior of the electrolyte through the foil 101. Otherwise, the migration of the electrolyte through the foil may impair or degrade the adhesion of the metal foil. This may lead to delamination, but such a thing is effectively prevented by embodiments of the present invention. The desired resistance can be achieved, for example, by using cast polypropylene, i.e., cast PP. The sealing layer 103 may have a thickness in the range of 2 μm to 20 μm, preferably in the range of 5% to 20% of the thickness of the foil 10.

[0016] Depending on the application, the above-mentioned layer thickness will be the total layer thickness d of the foil 10. For example, when used in mobile devices, the total layer thickness d of the foil may be 30 to 50 μm or, for example, 40 μm. For high-voltage batteries in the automotive industry, the foil thickness may be in the range of 70 μm to 90 μm, preferably about 80 μm. When aluminum is selected as the metal, the foil 10 can be called aluminum laminated foil, abbreviated as ALF (aluminium laminated foil), which is preferably provided as a three-layer co-extruded foil made of CPP for lamination.

[0017] Figure 2 schematically shows the basic structure of a package intermediate product or housing intermediate product having a foil according to one embodiment of the present invention. A semi-finished product 20 is particularly shown, which is also in the form of a film or plate and comprises a foil 10 for forming a package or housing as described elsewhere in this specification. Furthermore, the semi-finished product 20 comprises a metal layer 200 in the form of a metal foil, a metal plate or sheet metal. This metal layer is preferably an aluminum foil having a material thickness in the range of 10 to 100 μm or 30 to 50 μm.

[0018] The semi-finished product 20 is bonded to the foil 10 using an adhesive 210, preferably a laminate adhesive, a two-component adhesive, or a polyurethane (PU) adhesive. In an advantageous embodiment, the foil 10 is first corona pre-treated, thereby improving its bondability to the metal layer 200 via the adhesive 210. Furthermore, an outer protective layer 300, made of, or containing, polyamide (PA) and / or polyethylene terephthalate (PET), for example, is placed on the metal layer 200. The protective layer 300 may be bonded to the metal layer 200 using an additional adhesive 320. The protective layer 300 may have a material thickness in the range of 10 to 30 μm or 15 to 20 μm. Thus, the typical layer thickness of the entire composite material 20 may be, for example, about 140 μm. When aluminum is used as the metal layer, this layer can be laminated in the form of at least three layers of composite material by bonding one side with the aforementioned co-extruded foil and polyamide foil using an adhesive system (e.g., co-extruded PP-aluminum-PA-PET).

[0019] Figures 3A to 3E schematically show the possible shapes of a package or housing member manufactured from foil according to one embodiment of the present invention. Figure 3A shows a simple pouch shape 910 obtained by folding a semi-finished product 20 into a rectangle along a fold 911 and welding the remaining sides in region 912. It is advantageous for the sealing layers 103 of the semi-finished product 20 to be joined at these points, and the welding can reliably seal the volume V (here, in the inset, multiple sealing layers 103 of semi-finished products 20A and 20B are fused in region 103A / B). One or more access points 914 can be provided in the welded region 912, which allow access to the internal volume V and provide, for example, electrical contacts in the case of a battery housing or a closure in the case of a package. A cross-sectional view of the pouch shape 910 with volume V along axis 913 is shown in the region on the right.

[0020] Further pouch shapes are shown in FIGS. 3B and 3C, and the pouch may have a basically rectangular basic shape like the pouch 920 (FIG. 3B), or may have any desired shape like the pouch 920' (FIG. 3C). By using the foil according to the present invention and the corresponding semi-finished product, pouches of almost any shape can be obtained by welding the corresponding edge regions 922, 932, and the respective sealing layers can again be superimposed on each other and welded. One or more access points 914 can also be provided on these shapes, and since the pouch structure using the foil or semi-finished product according to the present invention provides great flexibility here, their positions can be arranged at the positions most suitable for the specific application. A cross-sectional view 920 / 920' of the volume V is schematically represented in both cases.

[0021] Figure 3D shows a cylindrical shape 940 obtained by simply rolling the semi-finished product 20. Cylindrical or cup-shaped pouches can also be produced by this method via at least one welding region 941. Figure 3E shows a prism-shaped pouch 950 obtained from the combination of one or more folds and one or more welding regions 951 (and optionally 952, 953).

[0022] Figure 4A schematically shows a possible use of the foil according to an embodiment of the present invention. In this application, a battery 980, which is for example a rechargeable battery, a lithium-ion battery, a lithium polymer battery, a solid-state battery, or the like, is provided. The electrolyte-containing structure comprises an electrode structure 981 and an electrolyte 983, and the inner sealing layer 103 of the semi-finished product 20 is in contact with the electrolyte 983 (see the inset). In pouch-type batteries, so-called "pouch cells", a plurality of rectangular layers of positive and negative electrodes and conductor foils are usually laminated in a sandwich form using corresponding separator layers. The electrodes are usually led out from one side. The outer covering and sealing is provided by deep-drawn welded plastic-aluminum-plastic multilayer foil.

[0023] The housing comprises a pouch manufactured from the foil 10 or the semi-finished product 20 according to the present invention, which is obtained by welding at least one region 987. This enables maximum flexibility with respect to the shape of the battery housing, and for example, corresponding batteries such as so-called pouch cells can be advantageously provided. An access point in the form of a contact 984 can be provided on one of the welding regions 987, from which a battery contact 985 is led out from the internal volume V to the outside of the assembly in an electrically insulated state.

[0024] In such applications, a semi-finished product, for example a pouch-type battery film structure of "CPP film-aluminum foil-PA foil", is formed into a (usually) rectangular cavity shape by stamping or compression molding, and two pieces having these shapes are sealed by heat welding or ultrasonic welding, whereby a housing for a battery assembly (coil and electrolyte) can be formed. After sealing (welding), the sealing layer remains permanently and reliably on the aluminum foil laminated by the adhesive system. Even if damage occurs or the service life expires, residual foil will remain on the metal layer (e.g., aluminum foil) in case the sealing seam peels or tears / separates. It should be noted here that "permanent" in the context of the present disclosure generally means lasting at least for the intended service life or service period of the product (package, housing, battery, etc.). Even in the worst-case scenario of delamination, embodiments of the present invention provide the significant advantage that the residual layer, for example PP, remains on the metal foil as a thin protective layer.

[0025] This is achieved, in particular with semi-finished composite structures, in that, under maximum load, the composite material within the foil breaks, i.e., the bonding layer delaminates from the core layer and / or the core layer delaminates from the (welded) sealing layer, while the metal foil remains protected from contact with the electrolyte by the residual foil. In either case, for example, a residual layer of foil remains on the aluminum, thus advantageously preventing the electrolyte from coming into contact with the aluminum foil. Interlayer delamination can also be confirmed by a so-called white break indicator, for example, where the PP layer remains on the aluminum foil.

[0026] Figure 4B schematically shows a possible use of the foil according to one embodiment of the present invention. In this use, an exemplary self-standing pouch package 990 is provided. For this purpose, a semi-finished product is manufactured by a combination of one or more folds 991 and one or more welded sections 992. By providing access points in the form of closures 993 in part of the welded area, the package can be filled and / or discharged. By using the foil 10 or semi-finished product 20 according to the present invention, a reliable product package can be realized, which can also reliably contain electrolyte-containing materials.

Claims

1. A foil for forming a package or housing, A bonding layer configured to bond to a metal foil, A core layer having a thickness at least half the thickness of the foil, A sealing layer configured to be in permanent contact with the electrolyte, A foil equipped with [a specific feature].

2. The bonding layer is configured to bond to the metal foil by undergoing a corona pretreatment that promotes bonding to the metal foil via an adhesion promoter. The foil as described in claim 1.

3. The aforementioned adhesion promoter comprises an adhesive or an adhesion system. The foil as described in claim 2.

4. The bonding layer is configured to bond to the metal foil by comprising an adhesion-promoting additive that facilitates bonding to the metal foil. The foil as described in claim 1.

5. The bonding layer is directly bonded to the metal foil by the adhesion-promoting additive. The foil as described in claim 4.

6. Even if the sealing layer is pre-moistened with an electrolyte, it will form a connection by welding or sealing. A foil as described in any one of claims 1 to 5.

7. The binding layer, the core layer and / or the sealing layer exist as a co-extruded structure. A foil as described in any one of claims 1 to 6.

8. The binding layer, the core layer and / or the sealing layer are made of polyolefin plastic. A foil as described in any one of claims 1 to 7.

9. The aforementioned polyolefin-based plastic is cast polypropylene or cast PP. The foil as described in claim 8.

10. A foil as described in any one of claims 1 to 9, A metal foil bonded to the aforementioned bonding layer, A semi-finished product for forming a package or housing, comprising the components mentioned above.

11. The aforementioned metal foil is aluminum foil. A semi-finished product as described in claim 10.

Images